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1.
Radiat Prot Dosimetry ; 150(4): 434-40, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22232779

RESUMO

Building regulations in Israel require the insulating of buildings against radon (222)Rn penetration from soil. In radon-prone areas membranes stretched between the soil and the building foundation are used, together with sealing other possible penetration routes. Designing the radon mitigation procedure requires checking that all sealing materials are practically, radon tight, having a thickness of at least three times the radon diffusion length. In this work, a very simple technique to evaluate the radon diffusion length in thin membranes, using a radon source of known activity and an activated charcoal canister as radon detector is presented. The theoretical formalism and measurement results for polyethylene membranes of different densities obtained in a recent comparison exercise are presented.


Assuntos
Poluentes Radioativos do Ar/química , Poluição do Ar em Ambientes Fechados/análise , Membranas Artificiais , Polietileno/química , Radônio/química , Materiais de Construção , Difusão , Teste de Materiais
2.
J Chromatogr B Analyt Technol Biomed Life Sci ; 852(1-2): 684-8, 2007 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-17383946

RESUMO

A sensitive and specific method has been developed to detect semi-quantitatively testosterone in horse hair samples. The method involved a washing step with sodium dodecylsulfate aqueous solution. The mane and tail hair samples (100mg) were dissolved in 1 mL of sodium hydroxide for 15 min at 95 degrees C in the presence of d3-boldenone used as internal standard. The next three steps involved diethyl ether extraction and a solid phase extraction on Isolute C18 (EC) cartridges eluted with methanol. The residue was derivatized by adding 100 microL of acetonitrile and 30 microL of PFPA then incubating for 15 min at 60 degrees C. After evaporation, 30 microL of hexane was added and 2.5 microL was injected into the column (a bonded phase fused silica capillary column DB5MS, 30 m x 0.25 mm i.d. x 0.25 microm film thickness) of a Trace GC chromatograph. In order to improve the sensitivity of the method, damping gas flow has been optimized. Testosterone was identified in MS(2) full scan mode on the Polaris Q instrument. The assay was capable of detecting less than 1 pg mg(-1). The recovery was close to 90%. The analysis of tail and mane samples collected from a gelding horse having received a single dose of testosterone propionate (1 mg kg(-1)) showed the presence of testosterone in the range of 1-6 pg mg(-1) in hair collected during 5 months after administration.


Assuntos
Dopagem Esportivo , Cromatografia Gasosa-Espectrometria de Massas/métodos , Cabelo/química , Detecção do Abuso de Substâncias/métodos , Propionato de Testosterona/análise , Animais , Cavalos , Propionato de Testosterona/administração & dosagem
3.
J Environ Radioact ; 82(3): 321-34, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15885378

RESUMO

Increased interest in measuring radionuclides and radon concentrations in fly ash, cement and other components of building products is due to the concern of health hazards of naturally occurring radioactive materials (NORM). The current work focuses on studying the influence of fly ash (FA) on radon-exhalation rate (radon flux) from cementitious materials. The tests were carried out on cement paste specimens with different FA contents. The first part of the paper presents the scientific background and describes the experiments, which we designed for testing the radon emanation of the raw materials used in the preparation of the cement-FA pastes. It is found that despite the higher (226)Ra content in FA (more than 3 times, compared with Portland cement) the radon emanation is significantly lower in FA (7.65% for cement vs. 0.52% only for FA).


Assuntos
Poluentes Radioativos do Ar/análise , Carbono , Materiais de Construção , Radônio/análise , Carvão Mineral , Cinza de Carvão , Material Particulado , Porosidade , Radioisótopos de Potássio/análise , Monitoramento de Radiação , Rádio (Elemento)/análise , Tório/análise
4.
J Environ Radioact ; 82(3): 335-50, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15885379

RESUMO

Increased interest in measuring radionuclides and radon concentrations in fly ash (FA), cement and other components of building products is due to the concern about health hazards of naturally occurring radioactive materials (NORM). The paper focuses on studying the influence of FA on radon exhalation rate (radon flux) from cementitious materials. In the previous part of the paper the state of the art was presented, and the experiments for testing raw materials, Portland cement and coal fly ash, were described. Since the cement and FA have the most critical role in the radon release process relative to other concrete constituents (sand and gravel), and their contribution is dominant in the overall radium content of concrete, tests were carried out on cement paste specimens with different FA contents, 0-60% by weight of the binder (cement+FA). It is found that the dosage of FA in cement paste has a limited influence on radon exhalation rate, if the hardened material is relatively dense. The radon flux of cement-FA pastes is lower than that of pure cement paste: it is about approximately 3 mBq m(-2) s(-1) for cement-FA pastes with FA content as high as 960 kg m(-3).


Assuntos
Poluentes Radioativos do Ar/análise , Carbono , Materiais de Construção , Rádio (Elemento)/análise , Radônio/análise , Carvão Mineral , Cinza de Carvão , Força Compressiva , Material Particulado , Porosidade , Monitoramento de Radiação/métodos
5.
Coll Antropol ; 25(1): 21-30, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11787543

RESUMO

Sexual dimorphism in stature, weight status and body composition were analyzed in a sample of 398 prepubertal children (213 girls, 185 boys) ageing between 7 and 10. Furthermore the prevalence of overweight was tested. Body composition parameters were determined using TBF 105 Body composition analyzer according to BIA-method. Highly significant sex differences in body composition were observed (p < 0.001). In contrast, stature, weight and BMI showed no significant differences between the two sexes. Nevertheless, a significant higher portion (p < 0.05) of girls (29%) corresponded to the definition overweight according to ASNS (Austrian Survey of Nutritional Status), while only 20% of the boys felt into the category overweight. The results of the present study showed not only significant sex differences in body composition, especially in fat mass, long before puberty onset, but also a significantly higher prevalence of overweight among prepubertal girls in comparison to prepubertal boys.


Assuntos
Composição Corporal , Peso Corporal , Desenvolvimento Infantil , Obesidade/epidemiologia , Caracteres Sexuais , Tecido Adiposo , Antropometria , Áustria/epidemiologia , Criança , Feminino , Humanos , Masculino , Prevalência , Puberdade , População Rural
6.
Phys Rev Lett ; 84(9): 1857-61, 2000 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-11017645

RESUMO

We report the first observation of the Cabibbo-suppressed charm baryon decay Xi(+)(c)-->pK(-)pi(+). We observe 150+/-22+/-5 events for the signal. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600 GeV/c Sigma(-) beam. The branching fractions of the decay relative to the Cabibbo-favored Xi(+)(c)-->Sigma+K-pi(+) and Xi(+)(c)-->Xi(-)pi(+)pi(+) are measured to be B(Xi(+)(c)-->pK(-)pi(+))/B(Xi(+)(c)-->Sigma+K-pi(+)) = 0.22+/-0. 06+/-0.03 and B(Xi(+)(c)-->pK(-)pi(+))/B(Xi(+)(c)-->Xi(-)pi(+)pi(+)) = 0.20+/-0.04+/-0.02, respectively.

7.
J Exp Med ; 192(8): 1165-74, 2000 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-11034606

RESUMO

Fas is a cell surface death receptor that signals apoptosis. Several proteins have been identified that bind to the cytoplasmic death domain of Fas. Fas-associated death domain (FADD), which couples Fas to procaspase-8, and Daxx, which couples Fas to the Jun NH(2)-terminal kinase pathway, bind independently to the Fas death domain. We have identified a 130-kD kinase designated Fas-interacting serine/threonine kinase/homeodomain-interacting protein kinase (FIST/HIPK3) as a novel Fas-interacting protein. Binding to Fas is mediated by a conserved sequence in the COOH terminus of the protein. FIST/HIPK3 is widely expressed in mammalian tissues and is localized both in the nucleus and in the cytoplasm. In transfected cell lines, FIST/HIPK3 causes FADD phosphorylation, thereby promoting FIST/HIPK3-FADD-Fas interaction. Although Fas ligand-induced activation of Jun NH(2)-terminal kinase is impaired by overexpressed active FIST/HIPK3, cell death is not affected. These results suggest that Fas-associated FIST/HIPK3 modulates one of the two major signaling pathways of Fas.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Apoptose , Proteínas de Transporte/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Saccharomyces cerevisiae , Receptor fas/metabolismo , Animais , Proteínas de Transporte/genética , Clonagem Molecular , Proteína de Domínio de Morte Associada a Fas , Feminino , Biblioteca Gênica , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas Quinases JNK Ativadas por Mitógeno , Células Jurkat , Masculino , Camundongos , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Especificidade de Órgãos , Fosforilação , Proteínas Recombinantes/metabolismo , Transcrição Gênica , Células Tumorais Cultivadas
8.
FEBS Lett ; 468(2-3): 129-33, 2000 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-10692572

RESUMO

The activation of the transcription factor NF-kappaB often results in protection against apoptosis. In particular, pro-apoptotic tumor necrosis factor (TNF) signals are blocked by proteins that are induced by NF-kappaB such as TNFR-associated factor 1 (TRAF1). Here we show that TRAF1 is cleaved after Asp-163 when cells are induced to undergo apoptosis by Fas ligand (FasL). The C-terminal cleavage product blocks the induction of NF-kappaB by TNF and therefore functions as a dominant negative (DN) form of TRAF1. Our results suggest that the generation of DN-TRAF1 is part of a pro-apoptotic amplification system to assure rapid cell death.


Assuntos
Apoptose/fisiologia , Caspases/metabolismo , Glicoproteínas de Membrana/fisiologia , Proteínas/fisiologia , Receptor fas/fisiologia , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose , Linfoma de Burkitt , Linhagem Celular , Proteína Ligante Fas , Fibrossarcoma , Humanos , Rim , Glicoproteínas de Membrana/farmacologia , NF-kappa B/metabolismo , Fragmentos de Peptídeos/farmacologia , Proteínas/antagonistas & inibidores , Proteínas/genética , Receptores do Fator de Necrose Tumoral/fisiologia , Proteínas Recombinantes/antagonistas & inibidores , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacologia , Transdução de Sinais , Fator 1 Associado a Receptor de TNF , Ligante Indutor de Apoptose Relacionado a TNF , Transfecção , Células Tumorais Cultivadas , Fator de Necrose Tumoral alfa/farmacologia
9.
J Exp Med ; 189(11): 1747-56, 1999 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-10359578

RESUMO

Members of the tumor necrosis factor (TNF) family induce pleiotropic biological responses, including cell growth, differentiation, and even death. Here we describe a novel member of the TNF family, designated BAFF (for B cell activating factor belonging to the TNF family), which is expressed by T cells and dendritic cells. Human BAFF was mapped to chromosome 13q32-34. Membrane-bound BAFF was processed and secreted through the action of a protease whose specificity matches that of the furin family of proprotein convertases. The expression of BAFF receptor appeared to be restricted to B cells. Both membrane-bound and soluble BAFF induced proliferation of anti-immunoglobulin M-stimulated peripheral blood B lymphocytes. Moreover, increased amounts of immunoglobulins were found in supernatants of germinal center-like B cells costimulated with BAFF. These results suggest that BAFF plays an important role as costimulator of B cell proliferation and function.


Assuntos
Linfócitos B/imunologia , Proteínas de Membrana/fisiologia , Receptores do Fator de Necrose Tumoral/fisiologia , Fator de Necrose Tumoral alfa/fisiologia , Sequência de Aminoácidos , Animais , Fator Ativador de Células B , Linfócitos B/citologia , Sequência de Bases , Divisão Celular , Linhagem Celular , Mapeamento Cromossômico , Cromossomos Humanos Par 13/genética , Clonagem Molecular , Primers do DNA/genética , Células Dendríticas/imunologia , Humanos , Ligantes , Ativação Linfocitária , Proteínas de Membrana/genética , Camundongos , Dados de Sequência Molecular , Receptores do Fator de Necrose Tumoral/genética , Homologia de Sequência de Aminoácidos , Linfócitos T/imunologia , Fator de Necrose Tumoral alfa/genética
10.
J Biol Chem ; 274(15): 9962-8, 1999 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-10187771

RESUMO

We have previously reported on the death effector domain containing E8 gene product from equine herpesvirus-2, designated FLICE inhibitory protein (v-FLIP), and on its cellular homologue, c-FLIP, which inhibit the activation of caspase-8 by death receptors. Here we report on the structure and function of the E10 gene product of equine herpesvirus-2, designated v-CARMEN, and on its cellular homologue, c-CARMEN, which contain a caspase-recruiting domain (CARD) motif. c-CARMEN is highly homologous to the viral protein in its N-terminal CARD motif but differs in its C-terminal extension. v-CARMEN and c-CARMEN interact directly in a CARD-dependent manner yet reveal different binding specificities toward members of the tumor necrosis factor receptor-associated factor (TRAF) family. v-CARMEN binds to TRAF6 and weakly to TRAF3 and, upon overexpression, potently induces the c-Jun N-terminal kinase (JNK), p38, and nuclear factor (NF)-kappaB transcriptional pathways. c-CARMEN or truncated versions thereof do not appear to induce JNK and NF-kappaB activation by themselves, nor do they affect the JNK and NF-kappaB activating potential of v-CARMEN. Thus, in contrast to the cellular homologue, v-CARMEN may have additional properties in its unique C terminus that allow for an autonomous activator effect on NF-kappaB and JNK. Through activation of NF-kappaB, v-CARMEN may regulate the expression of the cellular and viral genes important for viral replication.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Apoptose , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Proteínas de Transporte/metabolismo , Caspases/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas Quinases Ativadas por Mitógeno , NF-kappa B/metabolismo , Homologia de Sequência de Aminoácidos , Proteínas Virais/metabolismo , Sequência de Aminoácidos , Animais , Proteína 10 de Linfoma CCL de Células B , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD , Ativação Enzimática , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno , Células Jurkat , Camundongos , Dados de Sequência Molecular , Proteínas de Neoplasias , Receptores do Fator de Necrose Tumoral/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno
11.
Int J Soc Psychiatry ; 44(2): 135-46, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9675633

RESUMO

Family interactive patterns were investigated in the relatives of 20 mentally retarded patients institutionalised in two centres in Northern Italy. Expressed emotion (EE) was used as evaluation instrument. The results show a surprisingly high rate (45%) of high EE, even in relatives of patients who did not live inside the family. High EE was positively correlated to the presence of behavioral disorders in the patients, as already shown for children with conduct disorders. Treatment implications are discussed; there is an opportunity for the implementation of a family psychoeducational approach, aimed both at managing the behavioural consequences of the disorder and at enhancing rehabilitation programmes.


Assuntos
Emoções Manifestas , Família/psicologia , Institucionalização , Deficiência Intelectual/psicologia , Adaptação Psicológica , Adolescente , Adulto , Feminino , Humanos , Deficiência Intelectual/reabilitação , Masculino , Pessoa de Meia-Idade , Determinação da Personalidade , Transtornos do Comportamento Social/psicologia , Transtornos do Comportamento Social/reabilitação
12.
Nature ; 388(6638): 190-5, 1997 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-9217161

RESUMO

The widely expressed protein Fas is a member of the tumour necrosis factor receptor family which can trigger apoptosis. However, Fas surface expression does not necessarily render cells susceptible to Fas ligand-induced death signals, indicating that inhibitors of the apoptosis-signalling pathway must exist. Here we report the characterization of an inhibitor of apoptosis, designated FLIP (for FLICE-inhibitory protein), which is predominantly expressed in muscle and lymphoid tissues. The short form, FLIPs, contains two death effector domains and is structurally related to the viral FLIP inhibitors of apoptosis, whereas the long form, FLIP(L), contains in addition a caspase-like domain in which the active-centre cysteine residue is substituted by a tyrosine residue. FLIPs and FLIP(L) interact with the adaptor protein FADD and the protease FLICE, and potently inhibit apoptosis induced by all known human death receptors. FLIP(L) is expressed during the early stage of T-cell activation, but disappears when T cells become susceptible to Fas ligand-mediated apoptosis. High levels of FLIP(L) protein are also detectable in melanoma cell lines and malignant melanoma tumours. Thus FLIP may be implicated in tissue homeostasis as an important regulator of apoptosis.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Apoptose , Proteínas de Transporte/fisiologia , Caspases , Peptídeos e Proteínas de Sinalização Intracelular , Sequência de Aminoácidos , Animais , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Caspase 8 , Caspase 9 , Células Cultivadas , Cromossomos Humanos Par 2 , Clonagem Molecular , Cisteína Endopeptidases/metabolismo , Proteína de Domínio de Morte Associada a Fas , Humanos , Ativação Linfocitária , Melanoma/metabolismo , Dados de Sequência Molecular , Homologia de Sequência de Aminoácidos , Linfócitos T/citologia , Linfócitos T/imunologia , Linfócitos T/metabolismo , Células Tumorais Cultivadas , Receptor fas/metabolismo
13.
Immunity ; 6(1): 79-88, 1997 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9052839

RESUMO

A novel member of the tumor necrosis factor (TNF) receptor family, designated TRAMP, has been identified. The structural organization of the 393 amino acid long human TRAMP is most homologous to TNF receptor 1. TRAMP is abundantly expressed on thymocytes and lymphocytes. Its extracellular domain is composed of four cysteine-rich domains, and the cytoplasmic region contains a death domain known to signal apoptosis. Overexpression of TRAMP leads to two major responses, NF-kappaB activation and apoptosis. TRAMP-induced cell death is inhibited by an inhibitor of ICE-like proteases, but not by Bcl-2. In addition, TRAMP does not appear to interact with any of the known apoptosis-inducing ligands of the TNF family.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Apoptose , Linfócitos/fisiologia , Receptores de Superfície Celular/fisiologia , Receptores do Fator de Necrose Tumoral/fisiologia , Sequência de Aminoácidos , Proteínas Reguladoras de Apoptose , Proteínas de Transporte/metabolismo , Cromossomos Humanos Par 1 , Citoplasma/química , Proteína Ligante Fas , Proteína de Domínio de Morte Associada a Fas , Expressão Gênica , Humanos , Ligantes , Glicoproteínas de Membrana/metabolismo , Dados de Sequência Molecular , Família Multigênica , NF-kappa B/fisiologia , RNA Mensageiro/genética , Receptores do Fator de Necrose Tumoral/genética , Membro 25 de Receptores de Fatores de Necrose Tumoral , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Transdução de Sinais , Ligante Indutor de Apoptose Relacionado a TNF , Fator de Necrose Tumoral alfa/metabolismo
15.
Perception ; 23(10): 1197-202, 1994.
Artigo em Inglês | MEDLINE | ID: mdl-7899035

RESUMO

The motion aftereffect demonstrates the existence of direction-selective mechanisms in the visual system. However, direction-selective cells exist within many visual areas, including V1 and MT/V5. Can motion aftereffects be generated within each of these areas? In visual cortical areas beyond V1 almost all cells are binocular, whereas a smaller percentage are binocular in V1. The degree of binocularity can be revealed psychophysically by assessing interocular transfer. Interocular transfer of motion aftereffects generated from expanding rotating, and translating dynamic random-dot patterns were therefore compared, since these stimuli should activate cells in higher visual areas selectively. Partial interocular transfer was found that was greater for expansion and rotation than for translation. The results support the involvement of higher visual areas in motion aftereffects to complex animation sequences.


Assuntos
Percepção de Movimento , Rotação , Feminino , Humanos , Masculino , Psicofísica , Visão Binocular , Córtex Visual/fisiologia
17.
Minerva Psichiatr ; 34(3): 163-72, 1993 Sep.
Artigo em Italiano | MEDLINE | ID: mdl-7905596

RESUMO

The authors present data from an experimental study conducted on 20 institutionalized mentally handicapped adult patients. Relevant family variables were investigated by means of the Expressed Emotion (EE) scales, then compared with similar variables obtained in a matched sample of 20 schizophrenic patients and their families. Results show, in relatives of mentally handicapped patients, a higher rate of Warmth than in relatives of schizophrenics (p = 0.009), while other EE scales appear to reach similar values in both groups. Within the mentally handicapped family group, a higher rate of Emotional Over-involvement (p = 0.046) is shown by relatives of patients treated with neuroleptic drugs. The presence of high Warmth and Emotional Over-involvement, together with low Criticism and Hostility, may be interpreted as adaptation by the families to an organic disease with very early onset, clearer ad less rejecting than schizophrenia.


Assuntos
Emoções , Família , Deficiência Intelectual/psicologia , Relações Interpessoais , Adolescente , Adulto , Animais , Antipsicóticos/uso terapêutico , Feminino , Humanos , Deficiência Intelectual/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Gravidez , Escalas de Graduação Psiquiátrica , Esquizofrenia , Psicologia do Esquizofrênico
18.
Biochemistry ; 31(8): 2294-8, 1992 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-1540584

RESUMO

Hirudin from the leech Hirudo medicinalis is a most powerful anticoagulant, and many isoforms have been described. In the present work, the primary structure of two hirudins from the leech Hirudinaria manillensis has been elucidated. The antithrombotic activity is similar to that of H. medicinalis hirudins although the sequence identity is below 60%. Surprisingly, the hirudins were found to be glycosylated at one site. Sugar analysis after methanolysis yielded fucose, galactose, and N-acetylgalactosamine. These results combined with data from matrix-assisted laser desorption ionization mass spectrometry, plasma desorption mass spectrometry, capillary zone electrophoresis, and lectin-binding tests indicate that the sequence is Fuc-Gal beta 1-3GalNAc-(O-threonine). This structure shows an interesting similarity to human blood group H determinants.


Assuntos
Hirudinas/química , Sanguessugas/química , Sequência de Aminoácidos , Aminoácidos/análise , Animais , Configuração de Carboidratos , Glicosilação , Hirudinas/genética , Hirudinas/farmacologia , Dados de Sequência Molecular , Alinhamento de Sequência , Homologia de Sequência do Ácido Nucleico , Relação Estrutura-Atividade , Trombina/antagonistas & inibidores
19.
Pept Res ; 5(1): 25-9, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1623300

RESUMO

Matrix-assisted laser desorption ionization mass spectroscopy (LDI MS), a novel method for analysis of large molecules, has been used for characterization of synthetic peptides and their by-products. The potential of LDI MS is demonstrated by analyzing crude synthetic peptides representing typical members of newly designed peptides and proteins. In the first case, a fragment condensation reaction yielding a highly hydrophobic six-helic bundle template-assembled synthetic protein (TASP) is monitored. Then, a crude 19-mer peptide designed to adopt an amphiphilic alpha-helical structure and its by-products from SPPS are identified. Finally, analysis of crude hirulog-1, a 20-mer peptide designed as a thrombin inhibitor, using C18 reversed phase high performance liquid chromatography (RP HPLC), capillary electrophoresis (CE) and LDI MS, manifests the potential of the latter method.


Assuntos
Espectrometria de Massas/métodos , Peptídeos/química , Sequência de Aminoácidos , Lasers , Conformação Molecular , Dados de Sequência Molecular , Trombina/antagonistas & inibidores
20.
J Chromatogr ; 586(1): 43-50, 1991 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-1806554

RESUMO

The retention behaviour of a six-helix bundle template-assembled synthetic protein (TASP) molecule and its amphiphilic building blocks was investigated. The TASP consists of a circular template, cyclo(1-12)[KG]6, and six identical potentially alpha-helical peptides of the sequence KLALKLALKALKLALKLA. As an alpha-helix, this peptide is amphiliphilic along the axis of its helix. Based on this sequence, the retention times of a set of acetylated peptides containing from seven to twenty amino acids on a Nucleosil C18 column were compared with another set of peptides with the same amino acid composition but a non-amphiphilic structure. Peptide elution was effected with linear trifluoroacetic acid (TFA)-water to TFA-acetonitrile gradients. The difference in retention times increased with peptide length; the 9-mers eluted at the same time, but there was a difference of 3.5 min for the 13-mers and 22.3 min for the 20-mer, indicating the induction of secondary structure on binding to the stationary phase. The same pair of 20-mers on Vydac C18, C4 and biphenyl columns gave differences in retention times of 23.2, 16.7 and 12.3 min respectively. The TASP molecule was irreversibly adsorbed to C18 stationary phases, whereas it was eluted from C4 and biphenyl columns as a single sharp peak. Several side-products resulting from the synthesis of the TASP molecule were identified by matrix-assisted laser desorption ionization mass spectroscopy. A comparison of the retention times of these side-products and the results of pre-column denaturation experiments indicated that the tertiary structure of the TASP molecule is maintained on binding to biphenyl and C4 columns.


Assuntos
Cromatografia Líquida de Alta Pressão , Peptídeos/química , Sequência de Aminoácidos , Fenômenos Químicos , Físico-Química , Dados de Sequência Molecular , Conformação Proteica , Desnaturação Proteica
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